1. Field of the Invention
This invention relates in general to a process and an apparatus for burnishing a workpiece and, more particularly, to a process and apparatus adapted for burnishing the annular thrust surface and wick slot oil ramps of a thrust bearing.
2. Description of the Prior Art
Numerous devices have been developed for burnishing workpieces. Burnishing as used herein means the requalifying of the surface material of the workpiece so that it is flat, extremely smooth, and compacted. The prior art devices typically achieve burnishing by moving a burnishing tool against the workpiece surface in one relative direction. Usually this is accomplished by a rotary action in one direction. However, there are problems with this type of rotary action on an annular surface in that it is difficult to keep the surface clean and to keep the tool from picking up material and scoring the surface because the tool continues to accumulate material as it rotates. In the case of burnishing annular powdered metal surfaces, keeping the surface and the tool clean during single direction rotation can be extremely difficult. Unlike the prior art, the present invention provides for rotary burnishing of annular surfaces in one direction and then in the opposite direction so that material does not accumulate and the surface and tool are kept clean to provide better and more efficient burnishing.
Numerous devices can also be used to burnish the thrust surface of thrust bearings. However, many thrust bearings as is well known in the art have oil wick slots. These slots hold a porous oil soaked wick which provides oil to the thrust surface of the bearing. These oil wick slots have chamfered oil ramps as is well known in the art which lead oil from the edge of the oil wick slots onto the thrust surface. None of the prior art devices provide for a single process and apparatus for burnishing these oil ramps and the annular thrust surface so that these surfaces become flat, extremely smooth, and compressed for better oil flow.
Other examples of possible prior art devices and processes are shown in the following patents:
Timken: U.S. Pat. No. 1,441,893 PA0 Maupin: U.S. Pat. No. 1,619,479 PA0 Langhammer: U.S. Pat. No. 1,944,246 PA0 Chambers: U.S. Pat. No. 3,059,315 PA0 Heim: U.S. Pat. No. 3,093,884 PA0 Estry: U.S. Pat. No. 3,281,919 PA0 Williams: U.S. Pat. No. 3,307,254 PA0 Kalen: U.S. Pat. No. 3,795,956 PA0 Benson: U.S. Pat. No. 3,818,559
The Timken patent discloses a method and an apparatus for burnishing the cones of roller bearings with rollers. The Maupin patent discloses a method and an apparatus for burnishing cylindrical bearing surfaces. The Langhammer patent discloses an apparatus for sizing journal bushing. The Chambers patent discloses a burnishing tool for the burnishing of the radial fillet of a counterbore. The Heim patent discloses an apparatus for burnishing telescoped bearings. The Estry patent discloses a diamond burnishing apparatus where the tool is pivotally mounted on a lever for the purpose of burnishing crankshafts and the like. The Williams patent discloses a burnishing tool head for simultaneous cutting and burnishing of a surface. The Kalen patent discloses a burnishing tool for arcuate surfaces. The Benson patent discloses a burnishing tool for burnishing the interior wall of a hollow cylindrical surface.
These patents show various burnishing devices but do not show a process or device for the burnishing of an annular thrust surface of a thrust bearing. Further, none disclose the concurrent burnishing of chamfered wick slot oil ramps. These devices disclose rotary motion in only one relative direction.